Dominant epistasis is shown by these Gene. And when they are inherited the They show a 12:3:1 phenotype ratio.
Explanation:
Whenever, A dominant allele of Gene A is present it will mask the either alleles of Gene B and express black color. If dominant allele of Gene A is absent then B will express itself Giving red color morphs. And if Both the genes lack their dominant allele then orange color morphs will be produced.
[]random breeding between heterozygous colour morphs are shown in the attachment].